ComboBox reset current on model changed (#5217)

---------

Co-authored-by: Simon Hausmann <simon.hausmann@slint.dev>

CHANGELOG.md

@@ -8,7 +8,9 @@ All notable changes to this project are documented in this file.
 ### Widgets
 
  - Added `placeholder-text` property to `TextEdit`.
-
+ - Fixed updating model of ComboBox does not change current-value
+ - Fixed set current-index of ComboBox to -1 does not reset current-value
+
 ## [1.6.0] - 2024-05-13
 
 ## General

internal/compiler/object_tree.rs

@@ -1297,7 +1297,7 @@ impl Element {
         }
 
         for ch in node.PropertyChangedCallback() {
-            if !diag.enable_experimental {
+            if !diag.enable_experimental && !tr.expose_internal_types {
                 diag.push_error(
                     "Change callbacks are experimental and not yet implemented in this version of Slint".into(),
                     &ch,

internal/compiler/passes/remove_aliases.rs

@@ -160,6 +160,14 @@ pub fn remove_aliases(doc: &Document, diag: &mut BuildDiagnostics) {
             }
         };
 
+        // Adjust the change callbacks
+        {
+            let mut elem = elem.borrow_mut();
+            if let Some(old_change_callback) = elem.change_callbacks.remove(remove.name()) {
+                elem.change_callbacks.insert(to.name().to_owned(), old_change_callback);
+            }
+        }
+
         // Remove the declaration
         {
             let mut elem = elem.borrow_mut();

internal/compiler/passes/remove_unused_properties.rs

@@ -31,6 +31,7 @@ pub fn remove_unused_properties(component: &Component) {
                     elem.property_declarations.remove(x);
                     elem.property_analysis.borrow_mut().remove(x);
                     elem.bindings.remove(x);
+                    elem.change_callbacks.remove(x);
                 }
             },
         );

internal/compiler/widgets/common/combobox-base.slint

@@ -14,12 +14,15 @@ export component ComboBoxBase {
     callback show-popup();
 
     public function select(index: int) {
-        if (!root.enabled) {
+        if !root.enabled {
             return;
         }
-
         root.current-index = index;
-        root.current-value = root.model[root.current-index];
+
+        if root.current-value != root.model[root.current-index] {
+            root.update-current-value();
+        }
+
         root.selected(root.current-value);
     }
 
@@ -31,6 +34,26 @@ export component ComboBoxBase {
         root.select(Math.min(root.current-index + 1, root.model.length - 1));
     }
 
+    function reset-current() {
+        root.current-index = 0;
+    }
+
+    function update-current-value() {
+        if root.current-index < 0 || root.current-index >= root.model.length {
+            root.current-value = "";
+            return;
+        }
+        root.current-value = root.model[root.current-index];
+    }
+
+    changed model => {
+        root.reset-current();
+    }
+
+    changed current-index => {
+        root.update-current-value();
+    }
+
     private property <length> scroll-delta: 2px;
 
     forward-focus: i-focus-scope;
@@ -40,7 +63,6 @@ export component ComboBoxBase {
             if (!self.enabled) {
                 return reject;
             }
-
             if (event.text == Key.UpArrow) {
                 root.move-selection-up();
                 return accept;
@@ -66,14 +88,12 @@ export component ComboBoxBase {
                     root.move-selection-down();
                     return accept;
                 }
-
                 if (event.delta-y > root.scroll-delta) {
                     root.move-selection-up();
                     return accept;
                 }
-
                 reject
             }
         }
     }
-}
+}

tests/cases/widgets/combobox.slint

@@ -23,15 +23,19 @@ export component TestCase inherits Window {
 
     in-out property current-index <=> box.current-index;
     in-out property current-value <=> box.current-value;
+    in-out property model <=> box.model;
     out property has-focus <=> box.has-focus;
 }
 
 /*
 
 
 ```rust
+use std::rc::Rc;
 use slint::platform::Key;
 use slint::SharedString;
+use slint::VecModel;
+use i_slint_backend_testing::mock_elapsed_time;
 
 let instance = TestCase::new().unwrap();
 
@@ -86,6 +90,16 @@ assert_eq!(instance.get_current_index(), 1);
 assert_eq!(instance.get_output(), "selected(Bbb,1)\nselected(Ccc,2)\nselected(Bbb,1)\n");
 instance.set_output(Default::default());
 
+// Set current-index to -1
+instance.set_current_index(-1);
+mock_elapsed_time(500);
+assert_eq!(instance.get_current_value(), &SharedString::from(""));
+
+// Replace model
+instance.set_model(Rc::new(VecModel::from_slice(&[SharedString::from("A"), SharedString::from("B")])).into());
+mock_elapsed_time(500);
+assert_eq!(instance.get_current_index(), 0);
+assert_eq!(instance.get_current_value(), &SharedString::from("A"));
 
 ```